In development of an automobile or the like case, optimizing a tire suspension system needs to be taken into account. In this case, a large number of conditions must be set, such as a tire's surface temperature, internal pressure and contact load, and further, the tire's material and shape. It takes a great deal of test time to set their optimum conditions. Besides, the effect of the mechanism or compliance of a suspension on a tire's performance needs to be examined. Therefore, in a computerized simulation, a complicated tire model is difficult to be used as it is when considering the optimization. On the other hand, in the case of a real running test, actual tire characteristics can be directly obtained, but it is difficult to reproduce a road surface condition or the like for the purpose of the optimization.
Therefore, instead of a real running test, various tire testing apparatus have been proposed.
For example, in Patent Document 1, a testing apparatus is given which is capable of measuring the characteristics of a tire itself which appear at a running time. However, in the testing apparatus of Patent Document 1, the characteristics of a vehicle are left out of account.
In addition, in a unit described in Patent Document 2, in order to reproduce the behavior of a suspension, an attempt is made to approach a real running-test state by giving a tire a force equivalent to a tire-holding force from an arithmetic unit. However, in the testing apparatus of Patent Document 2, a fluctuation in the tire's side force changes the behavior of the vehicle including the suspension. This makes it hard to reproduce the real running state truly.
On the other hand, in a testing apparatus described in Patent Document 3, a simulation model which reproduces a vehicle model is incorporated into the corresponding unit. This is aimed at coming closer to a real running-test state. However, in the testing apparatus of Patent Document 3, the simulation model includes a tire model. Hence, in order to optimize the characteristics of a tire, another tire model needs creating anew, thus taking time and labor.
Therefore, as a unit which is capable of resolving the above described disadvantages, an HIL simulator is proposed (refer to Non-Patent Document 1). In this unit, a vehicle model corresponding to a simulation model using software is connected via an interface to a tire testing apparatus having a real tire as hardware. This tire HIL simulator is configured as a unit which has a real tire as hardware, without using a complex tire model as software. Hence, a test can be conducted under the conditions close to real running conditions.
Patent Document 1: Japanese Patent Laid-Open Publication No. 57-91440
Patent Document 2: Japanese Patent Laid-Open Publication No. 5-5677
Patent Document 3: Japanese Patent Laid-Open Publication No. 10-2842
Non-Patent Document 1: “134 Study on Handling and Stability by Using Tire HIL Simulator (Part 1)”, Academic Lecture Preprint Collection No. 101-02 (pp. 14-19) “2002593” by Society of Automotive Engineers of Japan, Inc.